1. Field of the Invention
The invention relates to a heating device, such as a fixing unit including a fixing belt, and to an image forming apparatus having the heating device.
2. Description of Related Art
An electrophotographic printer transfers a toner image corresponding to a print image to a paper sheet and fixes the toner image to the paper sheet by pressure and heat.
A conventional fixing unit includes a heating roller, a fixing roller, a fixing belt (endless belt) extending between and wound around the heating roller and the fixing roller, and a pressure roller that is provided outside the fixing belt and pressed against the fixing roller via the fixing belt and has therein a heater. The heating roller heats the fixing belt, and the heated belt and the pressure roller pressed against the heated belt presses and heats a paper sheet, onto which a toner image has been transferred and which is conveyed through the nip between the heated belt and the pressure roller, thereby fixing the toner image to the paper sheet (for example, Japanese Patent Application Laid-Open No. 2005-242111, Paragraphs 0008 to 0017 and FIG. 2).